The Blast fusion hammer is used at the Dragon Forge to combine the three ruined dragon armour pieces into a dragon platebody. This requires a Smithing level of 92 or higher. The hammer is only sold by the Foreman at the Blast Furnace in Keldagrim for 1,000,000 coins. The hammer can only be used to repair one platebody; afterwards it will crumble to dust. The blast fusion hammer can also be used to switch between the Melee, Magic, and Ranged versions of the dragonfire shield by taking it to the Dragon Forge. It will use up one hammer per shield, and requires a Smithing level of 92.

The hammer can also be used for regular smithing and will not disappear. However the hammer may not be used to smith together godsword shards to make a blade (this is likely an oversight by Jagex).

The hammer also has different appearance while smithing to a regular hammer, with a closer appearance to a chisel on the top half, and a regular hammer on the bottom. Despite this, it cannot be used to cut gems.

If unused, the Blast Fusion Hammer can be sold back to the Blast Furnace Foreman for the full 1,000,000 coins originally paid for it. Smithing regular metal does not reduce the price in any way.

The Blast fusion hammer can only be bought after completion of the Grandmaster quest, While Guthix Sleeps.

Initially, the Blast fusion hammer was one of the items needed to make the Imcando pickaxe, however as it requires completion of While Guthix Sleeps it was replaced by a requirement of 1,000,000 coins.